Behavioural Ecology of Sticklebacks

Abstract

Four problems currently dominate the study of animal ecology. First, electrophoretic studies have shown that natural populations are characterised by high levels of genetic variation, but there is controversy about the processes which maintain this variation (Lewontin 1974). Secondly, natural populations show greater or lesser fluctuations in abundance; some of these fluctuations are caused by abiotic factors but some reflect the effects of biotic interactions such as predation and parasitism. The relative importance of abiotic and biotic factors and the effect of the population’s own density on its changes in abundance have to be estimated. Age-specific birth and death rates categorise the life-history pattern of a species. This pattern is assumed to have adaptive significance, but the third problem is to develop a theory of life histories that will identify that significance and yield predictions of how the life-history pattern is likely to change in the face of changes in the environment. The fourth problem is to determine the factors that control the number of species that can coexist in a given area, particularly to assess the relative role of deterministic and stochastic processes in the pattern of colonisations and extinctions in a community. Because the behaviour of an animal mediates its interaction with the environment, any solutions to these problems will demand a knowledge of the behavioural responses of the animal to its abiotic and biotic environment (see also Pitcher, Kennedy and Wirjoatmodjo 1979). The sticklebacks (Gasterosteidae) provide unusually favourable material for revealing the importance of the study of behaviour to the analysis of ecological problems. These small fish have a wide geographical distribution. They frequently adapt well to laboratory conditions and they have a sufficiently short lifespan that all stages in their ontogeny can be studied experimentally. Their behaviour not only provides a behavioural ecologist with the raw material for research; it also yields a continuing aesthetic pleasure.